mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 17:30:02 +00:00
![Linus Torvalds](/assets/img/avatar_default.png)
-----BEGIN PGP SIGNATURE-----
iHUEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCYCegywAKCRCRxhvAZXjc
ouJ6AQDlf+7jCQlQdeKKoN9QDFfMzG1ooemat36EpRRTONaGuAD8D9A4sUsG4+5f
4IU5Lj9oY4DEmF8HenbWK2ZHsesL2Qg=
=yPaw
-----END PGP SIGNATURE-----
Merge tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull idmapped mounts from Christian Brauner:
"This introduces idmapped mounts which has been in the making for some
time. Simply put, different mounts can expose the same file or
directory with different ownership. This initial implementation comes
with ports for fat, ext4 and with Christoph's port for xfs with more
filesystems being actively worked on by independent people and
maintainers.
Idmapping mounts handle a wide range of long standing use-cases. Here
are just a few:
- Idmapped mounts make it possible to easily share files between
multiple users or multiple machines especially in complex
scenarios. For example, idmapped mounts will be used in the
implementation of portable home directories in
systemd-homed.service(8) where they allow users to move their home
directory to an external storage device and use it on multiple
computers where they are assigned different uids and gids. This
effectively makes it possible to assign random uids and gids at
login time.
- It is possible to share files from the host with unprivileged
containers without having to change ownership permanently through
chown(2).
- It is possible to idmap a container's rootfs and without having to
mangle every file. For example, Chromebooks use it to share the
user's Download folder with their unprivileged containers in their
Linux subsystem.
- It is possible to share files between containers with
non-overlapping idmappings.
- Filesystem that lack a proper concept of ownership such as fat can
use idmapped mounts to implement discretionary access (DAC)
permission checking.
- They allow users to efficiently changing ownership on a per-mount
basis without having to (recursively) chown(2) all files. In
contrast to chown (2) changing ownership of large sets of files is
instantenous with idmapped mounts. This is especially useful when
ownership of a whole root filesystem of a virtual machine or
container is changed. With idmapped mounts a single syscall
mount_setattr syscall will be sufficient to change the ownership of
all files.
- Idmapped mounts always take the current ownership into account as
idmappings specify what a given uid or gid is supposed to be mapped
to. This contrasts with the chown(2) syscall which cannot by itself
take the current ownership of the files it changes into account. It
simply changes the ownership to the specified uid and gid. This is
especially problematic when recursively chown(2)ing a large set of
files which is commong with the aforementioned portable home
directory and container and vm scenario.
- Idmapped mounts allow to change ownership locally, restricting it
to specific mounts, and temporarily as the ownership changes only
apply as long as the mount exists.
Several userspace projects have either already put up patches and
pull-requests for this feature or will do so should you decide to pull
this:
- systemd: In a wide variety of scenarios but especially right away
in their implementation of portable home directories.
https://systemd.io/HOME_DIRECTORY/
- container runtimes: containerd, runC, LXD:To share data between
host and unprivileged containers, unprivileged and privileged
containers, etc. The pull request for idmapped mounts support in
containerd, the default Kubernetes runtime is already up for quite
a while now: https://github.com/containerd/containerd/pull/4734
- The virtio-fs developers and several users have expressed interest
in using this feature with virtual machines once virtio-fs is
ported.
- ChromeOS: Sharing host-directories with unprivileged containers.
I've tightly synced with all those projects and all of those listed
here have also expressed their need/desire for this feature on the
mailing list. For more info on how people use this there's a bunch of
talks about this too. Here's just two recent ones:
https://www.cncf.io/wp-content/uploads/2020/12/Rootless-Containers-in-Gitpod.pdf
https://fosdem.org/2021/schedule/event/containers_idmap/
This comes with an extensive xfstests suite covering both ext4 and
xfs:
https://git.kernel.org/brauner/xfstests-dev/h/idmapped_mounts
It covers truncation, creation, opening, xattrs, vfscaps, setid
execution, setgid inheritance and more both with idmapped and
non-idmapped mounts. It already helped to discover an unrelated xfs
setgid inheritance bug which has since been fixed in mainline. It will
be sent for inclusion with the xfstests project should you decide to
merge this.
In order to support per-mount idmappings vfsmounts are marked with
user namespaces. The idmapping of the user namespace will be used to
map the ids of vfs objects when they are accessed through that mount.
By default all vfsmounts are marked with the initial user namespace.
The initial user namespace is used to indicate that a mount is not
idmapped. All operations behave as before and this is verified in the
testsuite.
Based on prior discussions we want to attach the whole user namespace
and not just a dedicated idmapping struct. This allows us to reuse all
the helpers that already exist for dealing with idmappings instead of
introducing a whole new range of helpers. In addition, if we decide in
the future that we are confident enough to enable unprivileged users
to setup idmapped mounts the permission checking can take into account
whether the caller is privileged in the user namespace the mount is
currently marked with.
The user namespace the mount will be marked with can be specified by
passing a file descriptor refering to the user namespace as an
argument to the new mount_setattr() syscall together with the new
MOUNT_ATTR_IDMAP flag. The system call follows the openat2() pattern
of extensibility.
The following conditions must be met in order to create an idmapped
mount:
- The caller must currently have the CAP_SYS_ADMIN capability in the
user namespace the underlying filesystem has been mounted in.
- The underlying filesystem must support idmapped mounts.
- The mount must not already be idmapped. This also implies that the
idmapping of a mount cannot be altered once it has been idmapped.
- The mount must be a detached/anonymous mount, i.e. it must have
been created by calling open_tree() with the OPEN_TREE_CLONE flag
and it must not already have been visible in the filesystem.
The last two points guarantee easier semantics for userspace and the
kernel and make the implementation significantly simpler.
By default vfsmounts are marked with the initial user namespace and no
behavioral or performance changes are observed.
The manpage with a detailed description can be found here:
1d7b902e28
In order to support idmapped mounts, filesystems need to be changed
and mark themselves with the FS_ALLOW_IDMAP flag in fs_flags. The
patches to convert individual filesystem are not very large or
complicated overall as can be seen from the included fat, ext4, and
xfs ports. Patches for other filesystems are actively worked on and
will be sent out separately. The xfstestsuite can be used to verify
that port has been done correctly.
The mount_setattr() syscall is motivated independent of the idmapped
mounts patches and it's been around since July 2019. One of the most
valuable features of the new mount api is the ability to perform
mounts based on file descriptors only.
Together with the lookup restrictions available in the openat2()
RESOLVE_* flag namespace which we added in v5.6 this is the first time
we are close to hardened and race-free (e.g. symlinks) mounting and
path resolution.
While userspace has started porting to the new mount api to mount
proper filesystems and create new bind-mounts it is currently not
possible to change mount options of an already existing bind mount in
the new mount api since the mount_setattr() syscall is missing.
With the addition of the mount_setattr() syscall we remove this last
restriction and userspace can now fully port to the new mount api,
covering every use-case the old mount api could. We also add the
crucial ability to recursively change mount options for a whole mount
tree, both removing and adding mount options at the same time. This
syscall has been requested multiple times by various people and
projects.
There is a simple tool available at
https://github.com/brauner/mount-idmapped
that allows to create idmapped mounts so people can play with this
patch series. I'll add support for the regular mount binary should you
decide to pull this in the following weeks:
Here's an example to a simple idmapped mount of another user's home
directory:
u1001@f2-vm:/$ sudo ./mount --idmap both:1000:1001:1 /home/ubuntu/ /mnt
u1001@f2-vm:/$ ls -al /home/ubuntu/
total 28
drwxr-xr-x 2 ubuntu ubuntu 4096 Oct 28 22:07 .
drwxr-xr-x 4 root root 4096 Oct 28 04:00 ..
-rw------- 1 ubuntu ubuntu 3154 Oct 28 22:12 .bash_history
-rw-r--r-- 1 ubuntu ubuntu 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 ubuntu ubuntu 3771 Feb 25 2020 .bashrc
-rw-r--r-- 1 ubuntu ubuntu 807 Feb 25 2020 .profile
-rw-r--r-- 1 ubuntu ubuntu 0 Oct 16 16:11 .sudo_as_admin_successful
-rw------- 1 ubuntu ubuntu 1144 Oct 28 00:43 .viminfo
u1001@f2-vm:/$ ls -al /mnt/
total 28
drwxr-xr-x 2 u1001 u1001 4096 Oct 28 22:07 .
drwxr-xr-x 29 root root 4096 Oct 28 22:01 ..
-rw------- 1 u1001 u1001 3154 Oct 28 22:12 .bash_history
-rw-r--r-- 1 u1001 u1001 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 u1001 u1001 3771 Feb 25 2020 .bashrc
-rw-r--r-- 1 u1001 u1001 807 Feb 25 2020 .profile
-rw-r--r-- 1 u1001 u1001 0 Oct 16 16:11 .sudo_as_admin_successful
-rw------- 1 u1001 u1001 1144 Oct 28 00:43 .viminfo
u1001@f2-vm:/$ touch /mnt/my-file
u1001@f2-vm:/$ setfacl -m u:1001:rwx /mnt/my-file
u1001@f2-vm:/$ sudo setcap -n 1001 cap_net_raw+ep /mnt/my-file
u1001@f2-vm:/$ ls -al /mnt/my-file
-rw-rwxr--+ 1 u1001 u1001 0 Oct 28 22:14 /mnt/my-file
u1001@f2-vm:/$ ls -al /home/ubuntu/my-file
-rw-rwxr--+ 1 ubuntu ubuntu 0 Oct 28 22:14 /home/ubuntu/my-file
u1001@f2-vm:/$ getfacl /mnt/my-file
getfacl: Removing leading '/' from absolute path names
# file: mnt/my-file
# owner: u1001
# group: u1001
user::rw-
user:u1001:rwx
group::rw-
mask::rwx
other::r--
u1001@f2-vm:/$ getfacl /home/ubuntu/my-file
getfacl: Removing leading '/' from absolute path names
# file: home/ubuntu/my-file
# owner: ubuntu
# group: ubuntu
user::rw-
user:ubuntu:rwx
group::rw-
mask::rwx
other::r--"
* tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: (41 commits)
xfs: remove the possibly unused mp variable in xfs_file_compat_ioctl
xfs: support idmapped mounts
ext4: support idmapped mounts
fat: handle idmapped mounts
tests: add mount_setattr() selftests
fs: introduce MOUNT_ATTR_IDMAP
fs: add mount_setattr()
fs: add attr_flags_to_mnt_flags helper
fs: split out functions to hold writers
namespace: only take read lock in do_reconfigure_mnt()
mount: make {lock,unlock}_mount_hash() static
namespace: take lock_mount_hash() directly when changing flags
nfs: do not export idmapped mounts
overlayfs: do not mount on top of idmapped mounts
ecryptfs: do not mount on top of idmapped mounts
ima: handle idmapped mounts
apparmor: handle idmapped mounts
fs: make helpers idmap mount aware
exec: handle idmapped mounts
would_dump: handle idmapped mounts
...
1402 lines
34 KiB
C
1402 lines
34 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* linux/fs/open.c
|
|
*
|
|
* Copyright (C) 1991, 1992 Linus Torvalds
|
|
*/
|
|
|
|
#include <linux/string.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/file.h>
|
|
#include <linux/fdtable.h>
|
|
#include <linux/fsnotify.h>
|
|
#include <linux/module.h>
|
|
#include <linux/tty.h>
|
|
#include <linux/namei.h>
|
|
#include <linux/backing-dev.h>
|
|
#include <linux/capability.h>
|
|
#include <linux/securebits.h>
|
|
#include <linux/security.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/fcntl.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/personality.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/syscalls.h>
|
|
#include <linux/rcupdate.h>
|
|
#include <linux/audit.h>
|
|
#include <linux/falloc.h>
|
|
#include <linux/fs_struct.h>
|
|
#include <linux/ima.h>
|
|
#include <linux/dnotify.h>
|
|
#include <linux/compat.h>
|
|
|
|
#include "internal.h"
|
|
|
|
int do_truncate(struct user_namespace *mnt_userns, struct dentry *dentry,
|
|
loff_t length, unsigned int time_attrs, struct file *filp)
|
|
{
|
|
int ret;
|
|
struct iattr newattrs;
|
|
|
|
/* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
|
|
if (length < 0)
|
|
return -EINVAL;
|
|
|
|
newattrs.ia_size = length;
|
|
newattrs.ia_valid = ATTR_SIZE | time_attrs;
|
|
if (filp) {
|
|
newattrs.ia_file = filp;
|
|
newattrs.ia_valid |= ATTR_FILE;
|
|
}
|
|
|
|
/* Remove suid, sgid, and file capabilities on truncate too */
|
|
ret = dentry_needs_remove_privs(dentry);
|
|
if (ret < 0)
|
|
return ret;
|
|
if (ret)
|
|
newattrs.ia_valid |= ret | ATTR_FORCE;
|
|
|
|
inode_lock(dentry->d_inode);
|
|
/* Note any delegations or leases have already been broken: */
|
|
ret = notify_change(mnt_userns, dentry, &newattrs, NULL);
|
|
inode_unlock(dentry->d_inode);
|
|
return ret;
|
|
}
|
|
|
|
long vfs_truncate(const struct path *path, loff_t length)
|
|
{
|
|
struct user_namespace *mnt_userns;
|
|
struct inode *inode;
|
|
long error;
|
|
|
|
inode = path->dentry->d_inode;
|
|
|
|
/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
|
|
if (S_ISDIR(inode->i_mode))
|
|
return -EISDIR;
|
|
if (!S_ISREG(inode->i_mode))
|
|
return -EINVAL;
|
|
|
|
error = mnt_want_write(path->mnt);
|
|
if (error)
|
|
goto out;
|
|
|
|
mnt_userns = mnt_user_ns(path->mnt);
|
|
error = inode_permission(mnt_userns, inode, MAY_WRITE);
|
|
if (error)
|
|
goto mnt_drop_write_and_out;
|
|
|
|
error = -EPERM;
|
|
if (IS_APPEND(inode))
|
|
goto mnt_drop_write_and_out;
|
|
|
|
error = get_write_access(inode);
|
|
if (error)
|
|
goto mnt_drop_write_and_out;
|
|
|
|
/*
|
|
* Make sure that there are no leases. get_write_access() protects
|
|
* against the truncate racing with a lease-granting setlease().
|
|
*/
|
|
error = break_lease(inode, O_WRONLY);
|
|
if (error)
|
|
goto put_write_and_out;
|
|
|
|
error = locks_verify_truncate(inode, NULL, length);
|
|
if (!error)
|
|
error = security_path_truncate(path);
|
|
if (!error)
|
|
error = do_truncate(mnt_userns, path->dentry, length, 0, NULL);
|
|
|
|
put_write_and_out:
|
|
put_write_access(inode);
|
|
mnt_drop_write_and_out:
|
|
mnt_drop_write(path->mnt);
|
|
out:
|
|
return error;
|
|
}
|
|
EXPORT_SYMBOL_GPL(vfs_truncate);
|
|
|
|
long do_sys_truncate(const char __user *pathname, loff_t length)
|
|
{
|
|
unsigned int lookup_flags = LOOKUP_FOLLOW;
|
|
struct path path;
|
|
int error;
|
|
|
|
if (length < 0) /* sorry, but loff_t says... */
|
|
return -EINVAL;
|
|
|
|
retry:
|
|
error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
|
|
if (!error) {
|
|
error = vfs_truncate(&path, length);
|
|
path_put(&path);
|
|
}
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
|
|
{
|
|
return do_sys_truncate(path, length);
|
|
}
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
|
|
{
|
|
return do_sys_truncate(path, length);
|
|
}
|
|
#endif
|
|
|
|
long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
|
|
{
|
|
struct inode *inode;
|
|
struct dentry *dentry;
|
|
struct fd f;
|
|
int error;
|
|
|
|
error = -EINVAL;
|
|
if (length < 0)
|
|
goto out;
|
|
error = -EBADF;
|
|
f = fdget(fd);
|
|
if (!f.file)
|
|
goto out;
|
|
|
|
/* explicitly opened as large or we are on 64-bit box */
|
|
if (f.file->f_flags & O_LARGEFILE)
|
|
small = 0;
|
|
|
|
dentry = f.file->f_path.dentry;
|
|
inode = dentry->d_inode;
|
|
error = -EINVAL;
|
|
if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
|
|
goto out_putf;
|
|
|
|
error = -EINVAL;
|
|
/* Cannot ftruncate over 2^31 bytes without large file support */
|
|
if (small && length > MAX_NON_LFS)
|
|
goto out_putf;
|
|
|
|
error = -EPERM;
|
|
/* Check IS_APPEND on real upper inode */
|
|
if (IS_APPEND(file_inode(f.file)))
|
|
goto out_putf;
|
|
sb_start_write(inode->i_sb);
|
|
error = locks_verify_truncate(inode, f.file, length);
|
|
if (!error)
|
|
error = security_path_truncate(&f.file->f_path);
|
|
if (!error)
|
|
error = do_truncate(file_mnt_user_ns(f.file), dentry, length,
|
|
ATTR_MTIME | ATTR_CTIME, f.file);
|
|
sb_end_write(inode->i_sb);
|
|
out_putf:
|
|
fdput(f);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
|
|
{
|
|
return do_sys_ftruncate(fd, length, 1);
|
|
}
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
|
|
{
|
|
return do_sys_ftruncate(fd, length, 1);
|
|
}
|
|
#endif
|
|
|
|
/* LFS versions of truncate are only needed on 32 bit machines */
|
|
#if BITS_PER_LONG == 32
|
|
SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
|
|
{
|
|
return do_sys_truncate(path, length);
|
|
}
|
|
|
|
SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
|
|
{
|
|
return do_sys_ftruncate(fd, length, 0);
|
|
}
|
|
#endif /* BITS_PER_LONG == 32 */
|
|
|
|
|
|
int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
|
|
{
|
|
struct inode *inode = file_inode(file);
|
|
long ret;
|
|
|
|
if (offset < 0 || len <= 0)
|
|
return -EINVAL;
|
|
|
|
/* Return error if mode is not supported */
|
|
if (mode & ~FALLOC_FL_SUPPORTED_MASK)
|
|
return -EOPNOTSUPP;
|
|
|
|
/* Punch hole and zero range are mutually exclusive */
|
|
if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
|
|
(FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
|
|
return -EOPNOTSUPP;
|
|
|
|
/* Punch hole must have keep size set */
|
|
if ((mode & FALLOC_FL_PUNCH_HOLE) &&
|
|
!(mode & FALLOC_FL_KEEP_SIZE))
|
|
return -EOPNOTSUPP;
|
|
|
|
/* Collapse range should only be used exclusively. */
|
|
if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
|
|
(mode & ~FALLOC_FL_COLLAPSE_RANGE))
|
|
return -EINVAL;
|
|
|
|
/* Insert range should only be used exclusively. */
|
|
if ((mode & FALLOC_FL_INSERT_RANGE) &&
|
|
(mode & ~FALLOC_FL_INSERT_RANGE))
|
|
return -EINVAL;
|
|
|
|
/* Unshare range should only be used with allocate mode. */
|
|
if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
|
|
(mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
|
|
return -EINVAL;
|
|
|
|
if (!(file->f_mode & FMODE_WRITE))
|
|
return -EBADF;
|
|
|
|
/*
|
|
* We can only allow pure fallocate on append only files
|
|
*/
|
|
if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
|
|
return -EPERM;
|
|
|
|
if (IS_IMMUTABLE(inode))
|
|
return -EPERM;
|
|
|
|
/*
|
|
* We cannot allow any fallocate operation on an active swapfile
|
|
*/
|
|
if (IS_SWAPFILE(inode))
|
|
return -ETXTBSY;
|
|
|
|
/*
|
|
* Revalidate the write permissions, in case security policy has
|
|
* changed since the files were opened.
|
|
*/
|
|
ret = security_file_permission(file, MAY_WRITE);
|
|
if (ret)
|
|
return ret;
|
|
|
|
if (S_ISFIFO(inode->i_mode))
|
|
return -ESPIPE;
|
|
|
|
if (S_ISDIR(inode->i_mode))
|
|
return -EISDIR;
|
|
|
|
if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
|
|
return -ENODEV;
|
|
|
|
/* Check for wrap through zero too */
|
|
if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
|
|
return -EFBIG;
|
|
|
|
if (!file->f_op->fallocate)
|
|
return -EOPNOTSUPP;
|
|
|
|
file_start_write(file);
|
|
ret = file->f_op->fallocate(file, mode, offset, len);
|
|
|
|
/*
|
|
* Create inotify and fanotify events.
|
|
*
|
|
* To keep the logic simple always create events if fallocate succeeds.
|
|
* This implies that events are even created if the file size remains
|
|
* unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
|
|
*/
|
|
if (ret == 0)
|
|
fsnotify_modify(file);
|
|
|
|
file_end_write(file);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(vfs_fallocate);
|
|
|
|
int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
|
|
{
|
|
struct fd f = fdget(fd);
|
|
int error = -EBADF;
|
|
|
|
if (f.file) {
|
|
error = vfs_fallocate(f.file, mode, offset, len);
|
|
fdput(f);
|
|
}
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
|
|
{
|
|
return ksys_fallocate(fd, mode, offset, len);
|
|
}
|
|
|
|
/*
|
|
* access() needs to use the real uid/gid, not the effective uid/gid.
|
|
* We do this by temporarily clearing all FS-related capabilities and
|
|
* switching the fsuid/fsgid around to the real ones.
|
|
*/
|
|
static const struct cred *access_override_creds(void)
|
|
{
|
|
const struct cred *old_cred;
|
|
struct cred *override_cred;
|
|
|
|
override_cred = prepare_creds();
|
|
if (!override_cred)
|
|
return NULL;
|
|
|
|
override_cred->fsuid = override_cred->uid;
|
|
override_cred->fsgid = override_cred->gid;
|
|
|
|
if (!issecure(SECURE_NO_SETUID_FIXUP)) {
|
|
/* Clear the capabilities if we switch to a non-root user */
|
|
kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
|
|
if (!uid_eq(override_cred->uid, root_uid))
|
|
cap_clear(override_cred->cap_effective);
|
|
else
|
|
override_cred->cap_effective =
|
|
override_cred->cap_permitted;
|
|
}
|
|
|
|
/*
|
|
* The new set of credentials can *only* be used in
|
|
* task-synchronous circumstances, and does not need
|
|
* RCU freeing, unless somebody then takes a separate
|
|
* reference to it.
|
|
*
|
|
* NOTE! This is _only_ true because this credential
|
|
* is used purely for override_creds() that installs
|
|
* it as the subjective cred. Other threads will be
|
|
* accessing ->real_cred, not the subjective cred.
|
|
*
|
|
* If somebody _does_ make a copy of this (using the
|
|
* 'get_current_cred()' function), that will clear the
|
|
* non_rcu field, because now that other user may be
|
|
* expecting RCU freeing. But normal thread-synchronous
|
|
* cred accesses will keep things non-RCY.
|
|
*/
|
|
override_cred->non_rcu = 1;
|
|
|
|
old_cred = override_creds(override_cred);
|
|
|
|
/* override_cred() gets its own ref */
|
|
put_cred(override_cred);
|
|
|
|
return old_cred;
|
|
}
|
|
|
|
static long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
|
|
{
|
|
struct path path;
|
|
struct inode *inode;
|
|
int res;
|
|
unsigned int lookup_flags = LOOKUP_FOLLOW;
|
|
const struct cred *old_cred = NULL;
|
|
|
|
if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
|
|
return -EINVAL;
|
|
|
|
if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
|
|
return -EINVAL;
|
|
|
|
if (flags & AT_SYMLINK_NOFOLLOW)
|
|
lookup_flags &= ~LOOKUP_FOLLOW;
|
|
if (flags & AT_EMPTY_PATH)
|
|
lookup_flags |= LOOKUP_EMPTY;
|
|
|
|
if (!(flags & AT_EACCESS)) {
|
|
old_cred = access_override_creds();
|
|
if (!old_cred)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
retry:
|
|
res = user_path_at(dfd, filename, lookup_flags, &path);
|
|
if (res)
|
|
goto out;
|
|
|
|
inode = d_backing_inode(path.dentry);
|
|
|
|
if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
|
|
/*
|
|
* MAY_EXEC on regular files is denied if the fs is mounted
|
|
* with the "noexec" flag.
|
|
*/
|
|
res = -EACCES;
|
|
if (path_noexec(&path))
|
|
goto out_path_release;
|
|
}
|
|
|
|
res = inode_permission(mnt_user_ns(path.mnt), inode, mode | MAY_ACCESS);
|
|
/* SuS v2 requires we report a read only fs too */
|
|
if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
|
|
goto out_path_release;
|
|
/*
|
|
* This is a rare case where using __mnt_is_readonly()
|
|
* is OK without a mnt_want/drop_write() pair. Since
|
|
* no actual write to the fs is performed here, we do
|
|
* not need to telegraph to that to anyone.
|
|
*
|
|
* By doing this, we accept that this access is
|
|
* inherently racy and know that the fs may change
|
|
* state before we even see this result.
|
|
*/
|
|
if (__mnt_is_readonly(path.mnt))
|
|
res = -EROFS;
|
|
|
|
out_path_release:
|
|
path_put(&path);
|
|
if (retry_estale(res, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
out:
|
|
if (old_cred)
|
|
revert_creds(old_cred);
|
|
|
|
return res;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
|
|
{
|
|
return do_faccessat(dfd, filename, mode, 0);
|
|
}
|
|
|
|
SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
|
|
int, flags)
|
|
{
|
|
return do_faccessat(dfd, filename, mode, flags);
|
|
}
|
|
|
|
SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
|
|
{
|
|
return do_faccessat(AT_FDCWD, filename, mode, 0);
|
|
}
|
|
|
|
SYSCALL_DEFINE1(chdir, const char __user *, filename)
|
|
{
|
|
struct path path;
|
|
int error;
|
|
unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
|
|
retry:
|
|
error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
|
|
if (error)
|
|
goto dput_and_out;
|
|
|
|
set_fs_pwd(current->fs, &path);
|
|
|
|
dput_and_out:
|
|
path_put(&path);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(fchdir, unsigned int, fd)
|
|
{
|
|
struct fd f = fdget_raw(fd);
|
|
int error;
|
|
|
|
error = -EBADF;
|
|
if (!f.file)
|
|
goto out;
|
|
|
|
error = -ENOTDIR;
|
|
if (!d_can_lookup(f.file->f_path.dentry))
|
|
goto out_putf;
|
|
|
|
error = file_permission(f.file, MAY_EXEC | MAY_CHDIR);
|
|
if (!error)
|
|
set_fs_pwd(current->fs, &f.file->f_path);
|
|
out_putf:
|
|
fdput(f);
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(chroot, const char __user *, filename)
|
|
{
|
|
struct path path;
|
|
int error;
|
|
unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
|
|
retry:
|
|
error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
|
|
if (error)
|
|
goto out;
|
|
|
|
error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
|
|
if (error)
|
|
goto dput_and_out;
|
|
|
|
error = -EPERM;
|
|
if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
|
|
goto dput_and_out;
|
|
error = security_path_chroot(&path);
|
|
if (error)
|
|
goto dput_and_out;
|
|
|
|
set_fs_root(current->fs, &path);
|
|
error = 0;
|
|
dput_and_out:
|
|
path_put(&path);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
int chmod_common(const struct path *path, umode_t mode)
|
|
{
|
|
struct inode *inode = path->dentry->d_inode;
|
|
struct inode *delegated_inode = NULL;
|
|
struct iattr newattrs;
|
|
int error;
|
|
|
|
error = mnt_want_write(path->mnt);
|
|
if (error)
|
|
return error;
|
|
retry_deleg:
|
|
inode_lock(inode);
|
|
error = security_path_chmod(path, mode);
|
|
if (error)
|
|
goto out_unlock;
|
|
newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
|
|
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
|
|
error = notify_change(mnt_user_ns(path->mnt), path->dentry,
|
|
&newattrs, &delegated_inode);
|
|
out_unlock:
|
|
inode_unlock(inode);
|
|
if (delegated_inode) {
|
|
error = break_deleg_wait(&delegated_inode);
|
|
if (!error)
|
|
goto retry_deleg;
|
|
}
|
|
mnt_drop_write(path->mnt);
|
|
return error;
|
|
}
|
|
|
|
int vfs_fchmod(struct file *file, umode_t mode)
|
|
{
|
|
audit_file(file);
|
|
return chmod_common(&file->f_path, mode);
|
|
}
|
|
|
|
SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
|
|
{
|
|
struct fd f = fdget(fd);
|
|
int err = -EBADF;
|
|
|
|
if (f.file) {
|
|
err = vfs_fchmod(f.file, mode);
|
|
fdput(f);
|
|
}
|
|
return err;
|
|
}
|
|
|
|
static int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
|
|
{
|
|
struct path path;
|
|
int error;
|
|
unsigned int lookup_flags = LOOKUP_FOLLOW;
|
|
retry:
|
|
error = user_path_at(dfd, filename, lookup_flags, &path);
|
|
if (!error) {
|
|
error = chmod_common(&path, mode);
|
|
path_put(&path);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
}
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
|
|
umode_t, mode)
|
|
{
|
|
return do_fchmodat(dfd, filename, mode);
|
|
}
|
|
|
|
SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
|
|
{
|
|
return do_fchmodat(AT_FDCWD, filename, mode);
|
|
}
|
|
|
|
int chown_common(const struct path *path, uid_t user, gid_t group)
|
|
{
|
|
struct user_namespace *mnt_userns;
|
|
struct inode *inode = path->dentry->d_inode;
|
|
struct inode *delegated_inode = NULL;
|
|
int error;
|
|
struct iattr newattrs;
|
|
kuid_t uid;
|
|
kgid_t gid;
|
|
|
|
uid = make_kuid(current_user_ns(), user);
|
|
gid = make_kgid(current_user_ns(), group);
|
|
|
|
mnt_userns = mnt_user_ns(path->mnt);
|
|
uid = kuid_from_mnt(mnt_userns, uid);
|
|
gid = kgid_from_mnt(mnt_userns, gid);
|
|
|
|
retry_deleg:
|
|
newattrs.ia_valid = ATTR_CTIME;
|
|
if (user != (uid_t) -1) {
|
|
if (!uid_valid(uid))
|
|
return -EINVAL;
|
|
newattrs.ia_valid |= ATTR_UID;
|
|
newattrs.ia_uid = uid;
|
|
}
|
|
if (group != (gid_t) -1) {
|
|
if (!gid_valid(gid))
|
|
return -EINVAL;
|
|
newattrs.ia_valid |= ATTR_GID;
|
|
newattrs.ia_gid = gid;
|
|
}
|
|
if (!S_ISDIR(inode->i_mode))
|
|
newattrs.ia_valid |=
|
|
ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
|
|
inode_lock(inode);
|
|
error = security_path_chown(path, uid, gid);
|
|
if (!error)
|
|
error = notify_change(mnt_userns, path->dentry, &newattrs,
|
|
&delegated_inode);
|
|
inode_unlock(inode);
|
|
if (delegated_inode) {
|
|
error = break_deleg_wait(&delegated_inode);
|
|
if (!error)
|
|
goto retry_deleg;
|
|
}
|
|
return error;
|
|
}
|
|
|
|
int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
|
|
int flag)
|
|
{
|
|
struct path path;
|
|
int error = -EINVAL;
|
|
int lookup_flags;
|
|
|
|
if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
|
|
goto out;
|
|
|
|
lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
|
|
if (flag & AT_EMPTY_PATH)
|
|
lookup_flags |= LOOKUP_EMPTY;
|
|
retry:
|
|
error = user_path_at(dfd, filename, lookup_flags, &path);
|
|
if (error)
|
|
goto out;
|
|
error = mnt_want_write(path.mnt);
|
|
if (error)
|
|
goto out_release;
|
|
error = chown_common(&path, user, group);
|
|
mnt_drop_write(path.mnt);
|
|
out_release:
|
|
path_put(&path);
|
|
if (retry_estale(error, lookup_flags)) {
|
|
lookup_flags |= LOOKUP_REVAL;
|
|
goto retry;
|
|
}
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
|
|
gid_t, group, int, flag)
|
|
{
|
|
return do_fchownat(dfd, filename, user, group, flag);
|
|
}
|
|
|
|
SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
|
|
{
|
|
return do_fchownat(AT_FDCWD, filename, user, group, 0);
|
|
}
|
|
|
|
SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
|
|
{
|
|
return do_fchownat(AT_FDCWD, filename, user, group,
|
|
AT_SYMLINK_NOFOLLOW);
|
|
}
|
|
|
|
int vfs_fchown(struct file *file, uid_t user, gid_t group)
|
|
{
|
|
int error;
|
|
|
|
error = mnt_want_write_file(file);
|
|
if (error)
|
|
return error;
|
|
audit_file(file);
|
|
error = chown_common(&file->f_path, user, group);
|
|
mnt_drop_write_file(file);
|
|
return error;
|
|
}
|
|
|
|
int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
|
|
{
|
|
struct fd f = fdget(fd);
|
|
int error = -EBADF;
|
|
|
|
if (f.file) {
|
|
error = vfs_fchown(f.file, user, group);
|
|
fdput(f);
|
|
}
|
|
return error;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
|
|
{
|
|
return ksys_fchown(fd, user, group);
|
|
}
|
|
|
|
static int do_dentry_open(struct file *f,
|
|
struct inode *inode,
|
|
int (*open)(struct inode *, struct file *))
|
|
{
|
|
static const struct file_operations empty_fops = {};
|
|
int error;
|
|
|
|
path_get(&f->f_path);
|
|
f->f_inode = inode;
|
|
f->f_mapping = inode->i_mapping;
|
|
f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
|
|
f->f_sb_err = file_sample_sb_err(f);
|
|
|
|
if (unlikely(f->f_flags & O_PATH)) {
|
|
f->f_mode = FMODE_PATH | FMODE_OPENED;
|
|
f->f_op = &empty_fops;
|
|
return 0;
|
|
}
|
|
|
|
if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
|
|
error = get_write_access(inode);
|
|
if (unlikely(error))
|
|
goto cleanup_file;
|
|
error = __mnt_want_write(f->f_path.mnt);
|
|
if (unlikely(error)) {
|
|
put_write_access(inode);
|
|
goto cleanup_file;
|
|
}
|
|
f->f_mode |= FMODE_WRITER;
|
|
}
|
|
|
|
/* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
|
|
if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
|
|
f->f_mode |= FMODE_ATOMIC_POS;
|
|
|
|
f->f_op = fops_get(inode->i_fop);
|
|
if (WARN_ON(!f->f_op)) {
|
|
error = -ENODEV;
|
|
goto cleanup_all;
|
|
}
|
|
|
|
error = security_file_open(f);
|
|
if (error)
|
|
goto cleanup_all;
|
|
|
|
error = break_lease(locks_inode(f), f->f_flags);
|
|
if (error)
|
|
goto cleanup_all;
|
|
|
|
/* normally all 3 are set; ->open() can clear them if needed */
|
|
f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
|
|
if (!open)
|
|
open = f->f_op->open;
|
|
if (open) {
|
|
error = open(inode, f);
|
|
if (error)
|
|
goto cleanup_all;
|
|
}
|
|
f->f_mode |= FMODE_OPENED;
|
|
if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
|
|
i_readcount_inc(inode);
|
|
if ((f->f_mode & FMODE_READ) &&
|
|
likely(f->f_op->read || f->f_op->read_iter))
|
|
f->f_mode |= FMODE_CAN_READ;
|
|
if ((f->f_mode & FMODE_WRITE) &&
|
|
likely(f->f_op->write || f->f_op->write_iter))
|
|
f->f_mode |= FMODE_CAN_WRITE;
|
|
|
|
f->f_write_hint = WRITE_LIFE_NOT_SET;
|
|
f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
|
|
|
|
file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
|
|
|
|
/* NB: we're sure to have correct a_ops only after f_op->open */
|
|
if (f->f_flags & O_DIRECT) {
|
|
if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
|
|
return -EINVAL;
|
|
}
|
|
|
|
/*
|
|
* XXX: Huge page cache doesn't support writing yet. Drop all page
|
|
* cache for this file before processing writes.
|
|
*/
|
|
if ((f->f_mode & FMODE_WRITE) && filemap_nr_thps(inode->i_mapping))
|
|
truncate_pagecache(inode, 0);
|
|
|
|
return 0;
|
|
|
|
cleanup_all:
|
|
if (WARN_ON_ONCE(error > 0))
|
|
error = -EINVAL;
|
|
fops_put(f->f_op);
|
|
if (f->f_mode & FMODE_WRITER) {
|
|
put_write_access(inode);
|
|
__mnt_drop_write(f->f_path.mnt);
|
|
}
|
|
cleanup_file:
|
|
path_put(&f->f_path);
|
|
f->f_path.mnt = NULL;
|
|
f->f_path.dentry = NULL;
|
|
f->f_inode = NULL;
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* finish_open - finish opening a file
|
|
* @file: file pointer
|
|
* @dentry: pointer to dentry
|
|
* @open: open callback
|
|
* @opened: state of open
|
|
*
|
|
* This can be used to finish opening a file passed to i_op->atomic_open().
|
|
*
|
|
* If the open callback is set to NULL, then the standard f_op->open()
|
|
* filesystem callback is substituted.
|
|
*
|
|
* NB: the dentry reference is _not_ consumed. If, for example, the dentry is
|
|
* the return value of d_splice_alias(), then the caller needs to perform dput()
|
|
* on it after finish_open().
|
|
*
|
|
* Returns zero on success or -errno if the open failed.
|
|
*/
|
|
int finish_open(struct file *file, struct dentry *dentry,
|
|
int (*open)(struct inode *, struct file *))
|
|
{
|
|
BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
|
|
|
|
file->f_path.dentry = dentry;
|
|
return do_dentry_open(file, d_backing_inode(dentry), open);
|
|
}
|
|
EXPORT_SYMBOL(finish_open);
|
|
|
|
/**
|
|
* finish_no_open - finish ->atomic_open() without opening the file
|
|
*
|
|
* @file: file pointer
|
|
* @dentry: dentry or NULL (as returned from ->lookup())
|
|
*
|
|
* This can be used to set the result of a successful lookup in ->atomic_open().
|
|
*
|
|
* NB: unlike finish_open() this function does consume the dentry reference and
|
|
* the caller need not dput() it.
|
|
*
|
|
* Returns "0" which must be the return value of ->atomic_open() after having
|
|
* called this function.
|
|
*/
|
|
int finish_no_open(struct file *file, struct dentry *dentry)
|
|
{
|
|
file->f_path.dentry = dentry;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(finish_no_open);
|
|
|
|
char *file_path(struct file *filp, char *buf, int buflen)
|
|
{
|
|
return d_path(&filp->f_path, buf, buflen);
|
|
}
|
|
EXPORT_SYMBOL(file_path);
|
|
|
|
/**
|
|
* vfs_open - open the file at the given path
|
|
* @path: path to open
|
|
* @file: newly allocated file with f_flag initialized
|
|
* @cred: credentials to use
|
|
*/
|
|
int vfs_open(const struct path *path, struct file *file)
|
|
{
|
|
file->f_path = *path;
|
|
return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
|
|
}
|
|
|
|
struct file *dentry_open(const struct path *path, int flags,
|
|
const struct cred *cred)
|
|
{
|
|
int error;
|
|
struct file *f;
|
|
|
|
validate_creds(cred);
|
|
|
|
/* We must always pass in a valid mount pointer. */
|
|
BUG_ON(!path->mnt);
|
|
|
|
f = alloc_empty_file(flags, cred);
|
|
if (!IS_ERR(f)) {
|
|
error = vfs_open(path, f);
|
|
if (error) {
|
|
fput(f);
|
|
f = ERR_PTR(error);
|
|
}
|
|
}
|
|
return f;
|
|
}
|
|
EXPORT_SYMBOL(dentry_open);
|
|
|
|
struct file *open_with_fake_path(const struct path *path, int flags,
|
|
struct inode *inode, const struct cred *cred)
|
|
{
|
|
struct file *f = alloc_empty_file_noaccount(flags, cred);
|
|
if (!IS_ERR(f)) {
|
|
int error;
|
|
|
|
f->f_path = *path;
|
|
error = do_dentry_open(f, inode, NULL);
|
|
if (error) {
|
|
fput(f);
|
|
f = ERR_PTR(error);
|
|
}
|
|
}
|
|
return f;
|
|
}
|
|
EXPORT_SYMBOL(open_with_fake_path);
|
|
|
|
#define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE))
|
|
#define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
|
|
|
|
inline struct open_how build_open_how(int flags, umode_t mode)
|
|
{
|
|
struct open_how how = {
|
|
.flags = flags & VALID_OPEN_FLAGS,
|
|
.mode = mode & S_IALLUGO,
|
|
};
|
|
|
|
/* O_PATH beats everything else. */
|
|
if (how.flags & O_PATH)
|
|
how.flags &= O_PATH_FLAGS;
|
|
/* Modes should only be set for create-like flags. */
|
|
if (!WILL_CREATE(how.flags))
|
|
how.mode = 0;
|
|
return how;
|
|
}
|
|
|
|
inline int build_open_flags(const struct open_how *how, struct open_flags *op)
|
|
{
|
|
int flags = how->flags;
|
|
int lookup_flags = 0;
|
|
int acc_mode = ACC_MODE(flags);
|
|
|
|
/* Must never be set by userspace */
|
|
flags &= ~(FMODE_NONOTIFY | O_CLOEXEC);
|
|
|
|
/*
|
|
* Older syscalls implicitly clear all of the invalid flags or argument
|
|
* values before calling build_open_flags(), but openat2(2) checks all
|
|
* of its arguments.
|
|
*/
|
|
if (flags & ~VALID_OPEN_FLAGS)
|
|
return -EINVAL;
|
|
if (how->resolve & ~VALID_RESOLVE_FLAGS)
|
|
return -EINVAL;
|
|
|
|
/* Scoping flags are mutually exclusive. */
|
|
if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT))
|
|
return -EINVAL;
|
|
|
|
/* Deal with the mode. */
|
|
if (WILL_CREATE(flags)) {
|
|
if (how->mode & ~S_IALLUGO)
|
|
return -EINVAL;
|
|
op->mode = how->mode | S_IFREG;
|
|
} else {
|
|
if (how->mode != 0)
|
|
return -EINVAL;
|
|
op->mode = 0;
|
|
}
|
|
|
|
/*
|
|
* In order to ensure programs get explicit errors when trying to use
|
|
* O_TMPFILE on old kernels, O_TMPFILE is implemented such that it
|
|
* looks like (O_DIRECTORY|O_RDWR & ~O_CREAT) to old kernels. But we
|
|
* have to require userspace to explicitly set it.
|
|
*/
|
|
if (flags & __O_TMPFILE) {
|
|
if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
|
|
return -EINVAL;
|
|
if (!(acc_mode & MAY_WRITE))
|
|
return -EINVAL;
|
|
}
|
|
if (flags & O_PATH) {
|
|
/* O_PATH only permits certain other flags to be set. */
|
|
if (flags & ~O_PATH_FLAGS)
|
|
return -EINVAL;
|
|
acc_mode = 0;
|
|
}
|
|
|
|
/*
|
|
* O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
|
|
* check for O_DSYNC if the need any syncing at all we enforce it's
|
|
* always set instead of having to deal with possibly weird behaviour
|
|
* for malicious applications setting only __O_SYNC.
|
|
*/
|
|
if (flags & __O_SYNC)
|
|
flags |= O_DSYNC;
|
|
|
|
op->open_flag = flags;
|
|
|
|
/* O_TRUNC implies we need access checks for write permissions */
|
|
if (flags & O_TRUNC)
|
|
acc_mode |= MAY_WRITE;
|
|
|
|
/* Allow the LSM permission hook to distinguish append
|
|
access from general write access. */
|
|
if (flags & O_APPEND)
|
|
acc_mode |= MAY_APPEND;
|
|
|
|
op->acc_mode = acc_mode;
|
|
|
|
op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
|
|
|
|
if (flags & O_CREAT) {
|
|
op->intent |= LOOKUP_CREATE;
|
|
if (flags & O_EXCL) {
|
|
op->intent |= LOOKUP_EXCL;
|
|
flags |= O_NOFOLLOW;
|
|
}
|
|
}
|
|
|
|
if (flags & O_DIRECTORY)
|
|
lookup_flags |= LOOKUP_DIRECTORY;
|
|
if (!(flags & O_NOFOLLOW))
|
|
lookup_flags |= LOOKUP_FOLLOW;
|
|
|
|
if (how->resolve & RESOLVE_NO_XDEV)
|
|
lookup_flags |= LOOKUP_NO_XDEV;
|
|
if (how->resolve & RESOLVE_NO_MAGICLINKS)
|
|
lookup_flags |= LOOKUP_NO_MAGICLINKS;
|
|
if (how->resolve & RESOLVE_NO_SYMLINKS)
|
|
lookup_flags |= LOOKUP_NO_SYMLINKS;
|
|
if (how->resolve & RESOLVE_BENEATH)
|
|
lookup_flags |= LOOKUP_BENEATH;
|
|
if (how->resolve & RESOLVE_IN_ROOT)
|
|
lookup_flags |= LOOKUP_IN_ROOT;
|
|
if (how->resolve & RESOLVE_CACHED) {
|
|
/* Don't bother even trying for create/truncate/tmpfile open */
|
|
if (flags & (O_TRUNC | O_CREAT | O_TMPFILE))
|
|
return -EAGAIN;
|
|
lookup_flags |= LOOKUP_CACHED;
|
|
}
|
|
|
|
op->lookup_flags = lookup_flags;
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* file_open_name - open file and return file pointer
|
|
*
|
|
* @name: struct filename containing path to open
|
|
* @flags: open flags as per the open(2) second argument
|
|
* @mode: mode for the new file if O_CREAT is set, else ignored
|
|
*
|
|
* This is the helper to open a file from kernelspace if you really
|
|
* have to. But in generally you should not do this, so please move
|
|
* along, nothing to see here..
|
|
*/
|
|
struct file *file_open_name(struct filename *name, int flags, umode_t mode)
|
|
{
|
|
struct open_flags op;
|
|
struct open_how how = build_open_how(flags, mode);
|
|
int err = build_open_flags(&how, &op);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
return do_filp_open(AT_FDCWD, name, &op);
|
|
}
|
|
|
|
/**
|
|
* filp_open - open file and return file pointer
|
|
*
|
|
* @filename: path to open
|
|
* @flags: open flags as per the open(2) second argument
|
|
* @mode: mode for the new file if O_CREAT is set, else ignored
|
|
*
|
|
* This is the helper to open a file from kernelspace if you really
|
|
* have to. But in generally you should not do this, so please move
|
|
* along, nothing to see here..
|
|
*/
|
|
struct file *filp_open(const char *filename, int flags, umode_t mode)
|
|
{
|
|
struct filename *name = getname_kernel(filename);
|
|
struct file *file = ERR_CAST(name);
|
|
|
|
if (!IS_ERR(name)) {
|
|
file = file_open_name(name, flags, mode);
|
|
putname(name);
|
|
}
|
|
return file;
|
|
}
|
|
EXPORT_SYMBOL(filp_open);
|
|
|
|
struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
|
|
const char *filename, int flags, umode_t mode)
|
|
{
|
|
struct open_flags op;
|
|
struct open_how how = build_open_how(flags, mode);
|
|
int err = build_open_flags(&how, &op);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
return do_file_open_root(dentry, mnt, filename, &op);
|
|
}
|
|
EXPORT_SYMBOL(file_open_root);
|
|
|
|
static long do_sys_openat2(int dfd, const char __user *filename,
|
|
struct open_how *how)
|
|
{
|
|
struct open_flags op;
|
|
int fd = build_open_flags(how, &op);
|
|
struct filename *tmp;
|
|
|
|
if (fd)
|
|
return fd;
|
|
|
|
tmp = getname(filename);
|
|
if (IS_ERR(tmp))
|
|
return PTR_ERR(tmp);
|
|
|
|
fd = get_unused_fd_flags(how->flags);
|
|
if (fd >= 0) {
|
|
struct file *f = do_filp_open(dfd, tmp, &op);
|
|
if (IS_ERR(f)) {
|
|
put_unused_fd(fd);
|
|
fd = PTR_ERR(f);
|
|
} else {
|
|
fsnotify_open(f);
|
|
fd_install(fd, f);
|
|
}
|
|
}
|
|
putname(tmp);
|
|
return fd;
|
|
}
|
|
|
|
long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
|
|
{
|
|
struct open_how how = build_open_how(flags, mode);
|
|
return do_sys_openat2(dfd, filename, &how);
|
|
}
|
|
|
|
|
|
SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
|
|
{
|
|
if (force_o_largefile())
|
|
flags |= O_LARGEFILE;
|
|
return do_sys_open(AT_FDCWD, filename, flags, mode);
|
|
}
|
|
|
|
SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
|
|
umode_t, mode)
|
|
{
|
|
if (force_o_largefile())
|
|
flags |= O_LARGEFILE;
|
|
return do_sys_open(dfd, filename, flags, mode);
|
|
}
|
|
|
|
SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
|
|
struct open_how __user *, how, size_t, usize)
|
|
{
|
|
int err;
|
|
struct open_how tmp;
|
|
|
|
BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
|
|
BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
|
|
|
|
if (unlikely(usize < OPEN_HOW_SIZE_VER0))
|
|
return -EINVAL;
|
|
|
|
err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
|
|
if (err)
|
|
return err;
|
|
|
|
/* O_LARGEFILE is only allowed for non-O_PATH. */
|
|
if (!(tmp.flags & O_PATH) && force_o_largefile())
|
|
tmp.flags |= O_LARGEFILE;
|
|
|
|
return do_sys_openat2(dfd, filename, &tmp);
|
|
}
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
/*
|
|
* Exactly like sys_open(), except that it doesn't set the
|
|
* O_LARGEFILE flag.
|
|
*/
|
|
COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
|
|
{
|
|
return do_sys_open(AT_FDCWD, filename, flags, mode);
|
|
}
|
|
|
|
/*
|
|
* Exactly like sys_openat(), except that it doesn't set the
|
|
* O_LARGEFILE flag.
|
|
*/
|
|
COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
|
|
{
|
|
return do_sys_open(dfd, filename, flags, mode);
|
|
}
|
|
#endif
|
|
|
|
#ifndef __alpha__
|
|
|
|
/*
|
|
* For backward compatibility? Maybe this should be moved
|
|
* into arch/i386 instead?
|
|
*/
|
|
SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
|
|
{
|
|
int flags = O_CREAT | O_WRONLY | O_TRUNC;
|
|
|
|
if (force_o_largefile())
|
|
flags |= O_LARGEFILE;
|
|
return do_sys_open(AT_FDCWD, pathname, flags, mode);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* "id" is the POSIX thread ID. We use the
|
|
* files pointer for this..
|
|
*/
|
|
int filp_close(struct file *filp, fl_owner_t id)
|
|
{
|
|
int retval = 0;
|
|
|
|
if (!file_count(filp)) {
|
|
printk(KERN_ERR "VFS: Close: file count is 0\n");
|
|
return 0;
|
|
}
|
|
|
|
if (filp->f_op->flush)
|
|
retval = filp->f_op->flush(filp, id);
|
|
|
|
if (likely(!(filp->f_mode & FMODE_PATH))) {
|
|
dnotify_flush(filp, id);
|
|
locks_remove_posix(filp, id);
|
|
}
|
|
fput(filp);
|
|
return retval;
|
|
}
|
|
|
|
EXPORT_SYMBOL(filp_close);
|
|
|
|
/*
|
|
* Careful here! We test whether the file pointer is NULL before
|
|
* releasing the fd. This ensures that one clone task can't release
|
|
* an fd while another clone is opening it.
|
|
*/
|
|
SYSCALL_DEFINE1(close, unsigned int, fd)
|
|
{
|
|
int retval = close_fd(fd);
|
|
|
|
/* can't restart close syscall because file table entry was cleared */
|
|
if (unlikely(retval == -ERESTARTSYS ||
|
|
retval == -ERESTARTNOINTR ||
|
|
retval == -ERESTARTNOHAND ||
|
|
retval == -ERESTART_RESTARTBLOCK))
|
|
retval = -EINTR;
|
|
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* close_range() - Close all file descriptors in a given range.
|
|
*
|
|
* @fd: starting file descriptor to close
|
|
* @max_fd: last file descriptor to close
|
|
* @flags: reserved for future extensions
|
|
*
|
|
* This closes a range of file descriptors. All file descriptors
|
|
* from @fd up to and including @max_fd are closed.
|
|
* Currently, errors to close a given file descriptor are ignored.
|
|
*/
|
|
SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd,
|
|
unsigned int, flags)
|
|
{
|
|
return __close_range(fd, max_fd, flags);
|
|
}
|
|
|
|
/*
|
|
* This routine simulates a hangup on the tty, to arrange that users
|
|
* are given clean terminals at login time.
|
|
*/
|
|
SYSCALL_DEFINE0(vhangup)
|
|
{
|
|
if (capable(CAP_SYS_TTY_CONFIG)) {
|
|
tty_vhangup_self();
|
|
return 0;
|
|
}
|
|
return -EPERM;
|
|
}
|
|
|
|
/*
|
|
* Called when an inode is about to be open.
|
|
* We use this to disallow opening large files on 32bit systems if
|
|
* the caller didn't specify O_LARGEFILE. On 64bit systems we force
|
|
* on this flag in sys_open.
|
|
*/
|
|
int generic_file_open(struct inode * inode, struct file * filp)
|
|
{
|
|
if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
|
|
return -EOVERFLOW;
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(generic_file_open);
|
|
|
|
/*
|
|
* This is used by subsystems that don't want seekable
|
|
* file descriptors. The function is not supposed to ever fail, the only
|
|
* reason it returns an 'int' and not 'void' is so that it can be plugged
|
|
* directly into file_operations structure.
|
|
*/
|
|
int nonseekable_open(struct inode *inode, struct file *filp)
|
|
{
|
|
filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(nonseekable_open);
|
|
|
|
/*
|
|
* stream_open is used by subsystems that want stream-like file descriptors.
|
|
* Such file descriptors are not seekable and don't have notion of position
|
|
* (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
|
|
* Contrary to file descriptors of other regular files, .read() and .write()
|
|
* can run simultaneously.
|
|
*
|
|
* stream_open never fails and is marked to return int so that it could be
|
|
* directly used as file_operations.open .
|
|
*/
|
|
int stream_open(struct inode *inode, struct file *filp)
|
|
{
|
|
filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
|
|
filp->f_mode |= FMODE_STREAM;
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(stream_open);
|